eslint-plugin-commander-option-flags

An ESLint plugin to enforce standard style for Commander.js option flags.

Features

• Format Check: Ensures flags are in the format -[char], --[word] (or just one of them).
• Internal Order: Enforces short flags to come before long flags (e.g., -p, --port instead of --port, -p).
• Alphabetical Sorting: Enforces chained .option() calls to be sorted alphabetically by flag name.

Installation

You'll first need to install ESLint:

npm i eslint --save-dev

Next, install eslint-plugin-commander-option-flags:

npm install eslint-plugin-commander-option-flags --save-dev

Prerequisites

This project pins the Node.js and npm versions using Volta. It is highly recommended to install Volta to ensure you are using the correct versions automatically.

Once you have Volta installed, just cd into the project directory, and Volta will switch to the pinned Node.js version.

Usage

Add commander-option-flags to the plugins section of your .eslintrc configuration file. You can omit the eslint-plugin- prefix:

{
    "plugins": [
        "commander-option-flags"
    ],
    "rules": {
        "commander-option-flags/commander-option-flags": "warn"
    }
}

Rule Details

Options

The rule accepts an optional object to configure the sorting order:

• order: "long" (default) or "short". Determines whether to sort based on the long flag name or the short flag name.

"commander-option-flags/commander-option-flags": ["warn", { "order": "long" }]

Examples

👎 Incorrect

program
  .option('--banana, -b') // Invalid order within string
  .option('-a, --apple') // Not sorted relative to previous
  .option('--port, -p <number>') // Long flag before short flag
  .option('port <number>') // Missing hyphens
  .option('-a, -b, --c') // Too many parts
  .option('-x, -x') // Duplicate short flags
  .option('--verbose, --verbose') // Duplicate long flags

👍 Correct

program
  .option('-a, --apple')
  .option('-b, --banana')
  .option('-p, --port <number>')
  .option('-s', 'short only')
  .option('--long', 'long only')

Implementation Details

The core logic is located in lib/rules/commander-option-flags.js. Here is a high-level overview of how it works:

1. AST Traversal: The rule listens for CallExpression nodes to identify calls to .option(). It specifically checks if the callee is a MemberExpression with the property name option.
2. Flag Parsing: It extracts the first argument (the flags string, e.g., "-p, --port <number>") and cleans it by removing argument placeholders (like <path> or [value]). The remaining string is split to identify potential short (-s) and long (--long) flags.
3. Validation Phases:
   • Format Check: Verifies that the flags strictly match the -[char] or --[word] patterns and ensures no duplicates exist.
   • Internal Order Check: Checks if both short and long flags are present. If so, it verifies that the short flag appears before the long flag in the string.
   • Sorting Check: It inspects the parent object to find the preceding chained call. If the previous call was also an .option(), it compares their flag names alphabetically (based on the order configuration).
4. Autofix Mechanism:
   • Internal Reordering: Reconstructs the flag string with the short flag first, preserving any trailing arguments.
   • Sorting: Uses fixer.replaceTextRange to swap the entire code range of the current .option(...) call with the preceding one.

TypeScript Support

This plugin works with TypeScript files parsed by @typescript-eslint/parser.

License

MIT